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avcodec/vc1dec: Limit bits by the actual bitstream size

Fixes: Timeout (350 ->19sec)
Fixes: 19249/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1IMAGE_fuzzer-6566896438870016

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit c56a52a82c0a4039e606e82b948a8abfe417f35f)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-12-08 19:37:46 +01:00
parent b4e369cf36
commit 5e874507e1

View File

@ -1012,7 +1012,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
ff_mpeg_er_frame_start(s);
v->bits = buf_size * 8;
v->bits = FFMIN(buf_size * 8, s->gb.size_in_bits);
v->end_mb_x = s->mb_width;
if (v->field_mode) {
s->current_picture.f->linesize[0] <<= 1;
@ -1084,8 +1084,10 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
continue;
}
ff_vc1_decode_blocks(v);
if (i != n_slices)
if (i != n_slices) {
s->gb = slices[i].gb;
v->bits = FFMIN(buf_size * 8, s->gb.size_in_bits);
}
}
if (v->field_mode) {
v->second_field = 0;